Bone remodeling of the fibula segment as a form of neocondyle after free vascularized bone transfer: a report of two cases.

The temporomandibular joint is a unique structure composed of the joint capsule, articular disc, mandibular condyles, glenoid fossa of the temporal bone, surrounding ligaments, and associated muscles. The condyle is one of the major components of a functional temporomandibular joint. Reconstruction of large mandibular defects involving the condyle is a surgical challenge for oral and maxillofacial surgeons. To restore large mandibular defects, there are different options for free flap method such as fibula, scapula, and iliac crest. Currently, the vascularized fibula free flap is the gold standard for reconstruction of complex mandibular defects involving the condyle. In the present report, neocondyle regeneration after mandible reconstruction including the condyle head with fibula free flap was evaluated. In this report, two patients were evaluated periodically, and remodeling of the distal end of the free fibula was observed in both cases after condylectomy or mandibulectomy. With preservation of the articular disc, trapezoidal shaping of the neocondyle, and elastic guidance of occlusion, neocondyle bone regeneration occured without ankylosis. Preservation of the articular disc and maintenance of proper occlusion are critical factors in regeneration of the neocondyle after mandible reconstruction.

Lesch-Nyhan syndrome: a case report.

Lesch-Nyhan syndrome (LNS) is a rare X-linked recessive disorder caused by a mutation in the hypoxanthine phosphoribosyltransferase 1 (HPRT1) gene. This syndrome is characterized by excessive production of uric acid, mental retardation, self-mutilation, choreoathetosis, and spasticity. The most distinctive symptom is compulsive self-mutilation. For patients with LNS, different methods have been tried to reduce self-biting behaviors including restraints, behavioral treatment, medications, deep brain stimulation, tooth extraction and botulinum toxin A injection. In this report, we present a case of LNS undergoing cheiloplasty due to self-mutilation and tooth extraction of the left deciduous maxillary canine.

The Assessment of Intermaxillary Fixation and Open Reduction Using Skeletal Anchorage System Compared With Arch Bar in Mandible Fracture Based on CT Image.

BACKGROUND: There are many different techniques to achieve intermaxillary fixation (IMF) for open reduction of mandible fractures. The arch bar has long been used as the gold standard of IMF to assist open reduction. However, owing to its long operating time, risk of needle stick injury, and gingival trauma, surgeons looked into different treatment options for IMF, such as the skeletal anchorage system (SAS). Therefore, this study aimed to compare the stability between IMF with arch bar and IMF with SAS based on computed tomography image. MATERIALS AND METHODS: In this retrospective study, postoperative computed tomography and panoramic radiographs were taken 1 week and 6 months after surgery, respectively. The treatment of mandibular fractures using IMF with arch bar and SAS were compared by evaluating changes in the dental midlines and condyle positions. Thirty patients with mandibular fractures were enrolled into 2 groups-IMF with arch bar and IMF with SAS. RESULTS: The arch bar showed slightly more deviation in dental midline. In SAS, the condyle moved more medially compared with the arch bar. CONCLUSIONS: Skeletal anchorage system could be used for IMF with reliable stability in mandible fracture. There were no significant differences in the treatment outcome between the 2 groups.

Features of Odontogenic Sinusitis Associated With Dental Implants.

OBJECTIVES: With the increase in dental implants for tooth loss, odontogenic sinusitis following maxillary dental implants is frequently encountered in otorhinolaryngology practice. The authors aimed to reveal the association between implant extrusion into maxillary sinus, along with implant-related complications in patients diagnosed with implant-related odontogenic sinusitis (IR-ODS). STUDY DESIGN: Case-control study. METHODS: This study enrolled 60 patients who received functional endoscopic sinus surgery due to IR-ODS. The preoperative sinus computed tomography was retrospectively reviewed. Among the 120 maxillary sinuses of the 60 patients, 68 sides were diagnosed with IR-ODS sides, whereas 27 sides showed no clinical or radiological evidence of this condition after the implant insertion and were defined as the control sides. Statistical analysis between these two groups was conducted, in addition to odds ratio (OR) calculations for associations with IR-ODS. RESULTS: The mean age of the IR-ODS subjects was 59.5 ± 19.1, with a male to female ratio of 32/28 (53.3%/46.7%). Implants extruding by more than 4 mm into the maxillary sinus, peri-implantitis, bone graft disruption-extrusion were associated with a significantly higher incidence in the IR-ODS (p = 0.035, p = 0.003, p = 0.011, respectively). The IR-ODS sides showed an adjusted-OR (95% confidence interval) of 27.4 (2.7-276.5) for extrusion length >4 mm, 11.8 (3.0-46.5) for peri-implantitis, and 34.1 (3.3-347.8) for bone graft disruption (p = 0.005, p < 0.001, and p = 0.003, respectively). CONCLUSION: Maxillary dental implants extruding more than 4 mm into the maxillary sinus, peri-implantitis, and disrupted-extruded bone grafts show significant association with IR-ODS. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:237-243, 2023.

The comprehensive on-demand 3D bio-printing for composite reconstruction of mandibular defects.

BACKGROUND: The mandible is a functional bio-organ that supports facial structures and helps mastication and speaking. Large mandible defects, generally greater than 6-cm segment loss, may require composite tissue reconstruction such as osteocutaneous-vascularized free flap which has a limitation of additional surgery and a functional morbidity at the donor site. A 3D bio-printing technology is recently developed to overcome the limitation in the composite reconstruction of the mandible using osteocutaneous-vascularized free flap. REVIEW: Scaffold, cells, and bioactive molecules are essential for a 3D bio-printing. For mandibular reconstruction, materials in a 3D bio-printing require mechanical strength, resilience, and biocompatibility. Recently, an integrated tissue and organ printing system with multiple cartridges are designed and it is capable of printing polymers to reinforce the printed structure, such as hydrogel. CONCLUSION: For successful composite tissue reconstruction of the mandible, biologic considerations and components should be presented with a comprehensive on-demand online platform model of customized approaches.

Biocompatibility evaluation of peo-treated magnesium alloy implants placed in rabbit femur condyle notches and paravertebral muscles.

BACKGROUND: Magnesium alloys have been receiving much attention for use in biodegradable metal implants because of their excellent mechanical properties and biocompatibility. However, their rapid breakdown and low bioactivity can cause the implant to lose mechanical integrity before the bone is completely healed. Moreover, hydrogen gas released during degradation can significantly delay the tissue regeneration process. To solve the instability of magnesium alloys, Zn and Ca can be added to improve the mechanical properties and biocompatibility. One other way to improve the mechanical properties of Mg is plasma electrolytic oxidation (PEO), which provides a dense, thick ceramic-like coating on the Mg surface. In this study, high-purity Mg was selected as the control, and Mg-1wt%Zn-0.1wt%Ca alloy and PEO-treated Mg-1wt%Zn-0.1wt%Ca alloy were selected as the test materials; the results of radiographic and histological analyses of their biocompatibility are reported herein. MATERIALS AND METHOD: Nineteen New Zealand white rabbits were used in the study. Rod-bars (Ø2.7 × 13.6 mm) were placed on both paravertebral muscles, and cannulated screws (Ø2.7x10mm) were placed on both femur condyle notches. Each animal was implanted in all four sites. X-rays were taken at 0, 2, 4, 8, and 12 weeks, micro-CT, and live-CT were taken at 4, 8, and 12 weeks. At weeks 4, 8, and 12, individuals representing each group were selected and sacrificed to prepare specimens for histopathological examination. RESULT: The results confirm that in vivo, Mg-1wt%Zn-0.1wt%Ca alloy had higher corrosion resistance than high-purity Mg and safely degraded over time without causing possible side effects (foreign body or inflammatory reactions, etc.). In addition, PEO treatment of Mg-1wt%Zn-0.1wt%Ca alloy had a positive effect on fracture recovery by increasing the bonding area with bone. CONCLUSION: Our results suggest that PEO treatment of Mg-1wt%Zn-0.1wt%Ca alloy can be a promising biomaterials in the field of various clinical situations such as orthopedic and maxillofacial surgerys.

The effect of FK506 (tacrolimus) loaded with collagen membrane and fibrin glue on promotion of nerve regeneration in a rat sciatic nerve traction injury model.

BACKGROUND: Peripheral nerve injury is one of the most common injuries that might occur in oral and maxillofacial surgery. The purpose of this study was to determine the effect of FK506 loaded with collagen membrane and fibrin glue on the promotion of nerve regeneration after traction nerve injury in a rat model. METHODS: Thirty male Sprague-Dawley rats were divided into three groups: group A (n = 10), a sham group whose sciatic nerve was exposed without any injury; and groups B (n = 10) and C (n = 10), which underwent traction nerve injury using 200 g of traction force for 1 min. The injured nerve in group C was covered with a collagen membrane soaked with FK506 (0.5 mg/0.1 mL) and fibrin glue. Functional analysis and microscopic evaluation were performed at 2 and 4 weeks after injury. RESULTS: The sciatic function index was - 5.78 ± 3.07 for group A, - 20.69 ± 5.22 for group B, and - 12.01 ± 4.20 for group C at 2 weeks after injury. However, at 4 weeks, the sciatic function index was - 5.58 ± 2.45 for group A, - 19.69 ± 4.81 for group B, and - 11.95 ± 1.94 for group C. In both periods, statistically significant differences were found among the groups (p<0.017). Histomorphometric evaluation revealed improved nerve regeneration in group C compared to that in group B. However, no statistical differences in axonal density were found among the three groups (p < 0.017). CONCLUSION: Localized FK506 with collagen membrane and fibrin glue could promote axonal regeneration in a rat model of traction nerve injury.